This invention relates to a fastening device for fastening a plurality of panels or the like, and more particularly, to a fastening device comprising female and male members of synthetic resin and designed to fasten at least two panels in the face-to-face contact.
It has been widely known that fasteners made of synthetic resin are extensively used in fitting together parts in automobiles and assembling electrical appliances, etc. Among these known fasteners are included fasteners of the kind composed of two members, male and female and designed to fasten a plurality of panels face to face. The most popular fastener of this kind comprises a female member of synthetic resin provided with a flange, a leg integrally connected to the lower surface of the flange and split lengthwise so as to allow lateral or radial expansion, and a bore made along the axial length of the leg from the upper center portion of the flange, and a male member made of metal adapted to advance into the bore of the female member thereby causing the leg to radially expand. This fastener has a construction such that two panels are fastened face to face by inserting the leg of the female member through the aperture of one of the panels until the flange comes into contact with the upper surface of the panel and then by laying the other panel on the upper side of the flange and subsequently threading the male member into the bore made along the axial direction from the upper center portion of the flange thereby fastening the latter panel to the upper side of the flange and, at the same time, causing the leg of the female member to expand radially within the aperture of the former panel. This fastener, therefore, entails a work of threading the male member as described above so as to fasten the two panels together.
This threading operation does not necessarily prove easy where numerous kinds of parts are fitted on products during an assembly line process. In an effort to overcome the difficulty, there has been proposed a fastener which uses a rod-shaped male member of synthetic resin in place of the aforementioned threaded male member and which provides the fastening together of two panels by simply driving the male member forcibly into the bore of the female member.
This forced entry type fastener for fastening parts has advantages over the screw-type fastener as described above since it effects the fastening by simply driving the male member forcibly into the bore of the female member. On the other hand, it has a disadvantage that when parts fastened therewith are required to be replaced with new ones, the male member driven forcibly into the bore must be extracted therefrom which involves arduous work. As a solution to this difficulty, there has been proposed a fastener wherein the male member is provided with a portion adapted to project from the upper surface of the flange of the female member when the male member has been driven home fixedly positioned within the bore of the female member. When the two members of the fastener are to be separated from each other, the extraction of the male member is accomplished by conveniently axially pulling the projection portion outward. Depending on the place at which the fastener is used, however, the protrusions of the projection portion may prove inconvenient. Particularly where parts are fitted in automobiles and electrical appliances, the projection portion may interfere with the fitting of other parts or impair the appearance of finished products. Also, the use of such fasteners may be impractical for reasons of poor safety.